My long term goal as a clinical scientist is to understand the pathogenesis of Kawasaki Syndrome (KS). I have concluded after intensive study of KS that a molecular approach is necessary to determine the etiologic agent and the pathogenesis of the illness. I propose to take a molecular approach to identifying the etiology of KS. My hypothesis is that either an RNA or a DNA virus causes KS. I have identified three approaches to cloning the etiologic agent of KS: 1) isolate, amplify, and clone viral nucleic acid from the serum of acute KS patients; 2) detect viral antigens in KS tissues by constructing cDNA and genomic expression libraries from the tissues and screening with convalescent patient sera; and 3) use an eukaryotic expression system to express viral antigens present in KS tissues. Significant preliminary data in my application attests to the feasibility of this approach in the identification of the etiologic agent of the illness.